1. Field of the Invention
This invention relates to a wide field eyepiece.
2. Description of the Prior Art
To facilitate observation of the entire field of view in an eyepiece, the eye relief should desirably be at least 80% or greater of the focal length of the eyepiece. It is known, however, that as the apparent field of view of the eyepiece is increased with various aberrations of the marginal rays maintained constant, the eye relief is decreased. Also, as the eye relief is increased with the apparent field of view maintained constant, the diameter of the lens system is increased, thus sharply aggravating the aberrations of the marginal rays in the field of view, particularly, coma, astigmatism and chromatic difference of magnification. It is thus very difficult to increase both the apparent field of view and the eye relief.